// interface Foo{
//   bar: number
// }
// let foo = {} as Foo
// foo.bar = 1
// let foo2: Foo ={
//   bar: 1
// }
type Handler = (a: number, b: number) => void
function hof(handler: Handler){
  return handler
}
let handler1 = (a: number) => {}
hof(handler1)
let handler2 = (a:number, b: number, c: number) => {}
// hof(handler2)
